It is known to convey discrete items composed of flexible sheet material along a path by passing each item through the nips of successive pairs of rollers, at least one roller of each pair being driven. Transport systems or conveyors of this kind have found use, inter alia, in photographic developing machines where they are used to convey completely developed and cut individual pictures through a drying section of the machine.
Known conveyors for this purpose have two or more roller pairs located along the transport path and separated from one another by a distance corresponding to the length of the items being moved. The relative arrangement of the roller pairs is such that their nips are in alignment -- i.e. at the nips all the rollers have a common tangential plane which also defines the transport or conveying path of the items being moved. A roller arrangement of such a kind assumes that the articles to be conveyed advance in a straight line and do not bend out of the plane of the conveying path. The tendency of the material to bend, e.g. due to gravity or to drying air acting on one side of the material or to increased surface tension on one side of the material, is particularly noticeable with very thin items, such as photographic papers or the like, and with these items is virtually unavoidable. In practice, therefore, guide elements in the form of appropriately devised metal members or meshes or the like are disposed between the discrete roller pairs to ensure that the items leaving one nip definitely enter the next nip. However, for various reasons guide elements of this kind are often undesirable and disturbing. Firstly, they impede ready access to the conveyed items when moving between the roller pairs, e.g. in respect of treatment with drying air or radiant heat, and secondly there is a risk, more particularly in the case of photographic papers, of surface damage caused by the guide elements.